<?php
echo "start\n";
$a = microtime(true);
Swoole\Coroutine\run(function () {
    for ($i=0;$i< 5;$i++) {
        Swoole\Coroutine::create(function (){
            Swoole\Coroutine::sleep(1);
        });
    }
});
echo microtime(true)-$a;